Power voltage supplier of semiconductor memory device

ABSTRACT

The present invention provides a power voltage supplier for stably supplying a noise-free power voltage without increasing a size of a reservoir capacitor by employing a sharing scheme of the reservoir capacitor. The power voltage supplier of a semiconductor memory device includes: a first power voltage supply line for supplying a first power voltage; a second power voltage supply line for supplying a second power voltage; a first reservoir capacitor for supplying the first and the second power voltages stably; and a reservoir capacitor controller for selectively connecting the first reservoir capacitor to the first power voltage supply line or the second power voltage supply line.

RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No.11/020,244, filed Dec. 27, 2004 and now issued as U.S. Pat. No.7,349,282, claiming priority of Korean Application No. 10-2004-0070846,filed September, the entire contents of each which are herebyincorporated by reference.

FIELD OF INVENTION

The present invention relates to a semiconductor memory device; and,more particularly, to a power voltage supplier of the semiconductormemory device capable of stably supplying a noise-free power voltage todrive the semiconductor memory device.

DESCRIPTION OF PRIOR ART

In recent years, a dynamic random access memory (DRAM) device requires ahigh-speed and a low operational voltage for its operation. Inparticular, since a threshold voltage variance of a transistor and itsmagnitude are key factors to determine a stability of a circuit in alow-voltage semiconductor memory device, it is necessary to stabilize avoltage source for supplying a power voltage.

Therefore, in order to stabilize the power voltage, a power voltagesupplier of the semiconductor memory device includes generally a powervoltage generator for generating a power voltage of a desired voltagelevel after receiving an external power voltage and a reservoircapacitor connected to an output node of the power voltage generator forkeeping the voltage level of the power voltage stable without noise.

FIG. 1 is a block diagram setting forth a prior art semiconductor memorydevice incorporating therein a power voltage supplier.

Referring to FIG. 1, the prior art semiconductor memory device includesa memory cell array 10 having a plurality of memory cells, a bit linesense amplifier (BLSA) array 20 having a plurality of bit line senseamplifiers, a VPP voltage supplier 30 for supplying a VPP voltage, aword line driver 40, a VDD voltage supplier 50 for supplying a VDDvoltage, a VCORE voltage supplier 60 for supplying a VCORE voltage, aBLSA driving control signal generator 70, an overdriving control signalgenerator 80 and a BLSA driver 90. The VPP voltage is higher than theVDD voltage and the VCORE voltage is lower than the VDD voltage, whereinthe VDD voltage is applied from an exterior voltage source.

Herein, the BLSA array 20 senses a potential difference of the bit linepair BL and /BL and amplifies a voltage level of a bit line pair BL and/BL of the memory cell array 10. The word line driver 40 drives a wordline WL of the memory cell array 10 arranged in a same row with the VPPvoltage in response to an active command signal ACT, to thereby activatethe memory cells corresponding to the word line WL. The BLSA drivingcontrol signal generator 70 generates a BLSA driving control signalSA_ACT in response to the active command signal ACT. The overdrivingcontrol signal generator 80 generates an overdriving control signal byreceiving the BLSA driving control signal SA_ACT.

The BLSA driver 90 generates a driving voltage signal RTO for drivingthe bit line sense amplifier with the VCORE voltage by receiving theBLSA driving control signal SA_ACT. In particular, the BLSA driver 90 isused for overdriving the bit line sense amplifier with the VDD voltageat an initial operation stage, in response to the overdriving controlsignal outputted from the overdriving control signal generator 80.Though it is not shown in the drawing, the voltage suppliers 30, 50 and60 include a respective reservoir capacitor at an output node thereof,for stabilizing an output voltage level from noise.

FIG. 2 is a timing diagram setting forth an operation of the prior artsemiconductor memory device.

To begin with, the word line driver 40 applies the VPP voltage to theword line WL of the memory cell array 10 in response to the activecommand signal ACT so that a data of the memory cell connected to theword line is applied to the bit line BL as a micro-voltage. Such anoperational period is denoted as A in FIG. 2. The BLSA driving controlsignal generator 70 activates the BLSA driving control signal SA_ACTafter a first predetermined time in response to the active commandsignal ACT. The overdriving control signal generator 80 activates theoverdriving control signal after a second predetermined time passes froman activation point of the BLSA driving control signal SA_ACT. The BLSAdriver 90 drives the bit line sense amplifier with the VCORE voltage inresponse to the BLSA driving control signal SA_ACT and particularlyoverdrives the bit line sense amplifier with the VDD voltage at theinitial operation stage when the overdriving control signal isactivated. Therefore, the bit line sense amplifier senses and amplifiesa data voltage applied to the bit line BL.

Thereafter, when a precharge command PCG is inputted, the word line WLis deactivated and the bit line pair BL and /BL is precharged to apredetermined voltage level VBLP, of which an operational period isdenoted as C in FIG. 2. Herein, a period denoted B in FIG. 2 is a periodthat the VDD voltage is applied for overdriving the bit line senseamplifier by means of the overdriving control signal.

As described above, the prior art semiconductor memory device uses theVPP voltage for activating a predetermined word line after receiving theactive command signal ACT. In addition, the VDD voltage is supplied tothe bit line sense amplifier instead of the VCORE voltage at the initialoperation stage of the bit line sense amplifier so that a plurality ofcharges are applied to the reservoir capacitor. Thus, it is possible toraise the voltage level applied to the bit line BL so as to enhance aRAS to CAS delay time (tRCD) and a write recovery time (tWR). Herein,the tRCD is a time difference between an input timing of a row addressand an input timing of a column address. The tWR is a minimum timerequired for stably storing the data into the unit cell not beingprevented by the precharge operation.

Meanwhile, since a plurality of memory cells, e.g., thousands of memorycells, connected to the same word line, the data of the bit line appliedby the activated word line are simultaneously sensed and amplified atthe bit line sense amplifiers so that the VDD voltage is consumed verymuch during sensing and amplification. As a result, there is happened aVDD voltage drop.

Therefore, in order to stabilize the voltage level of the VDD voltage atthe initial operation stage of the bit line sense amplifier, there hasbeen introduced a method of increasing a size of the reservoir capacitorin the VDD voltage supplier. However, in case of increasing thereservoir capacitor size on the basis of the case that maximum VDDvoltage is consumed, a cell area should be inevitably increased so thatit is difficult to fabricate the highly integrated memory device with amicronized scale. Thus, to address the above problem, it is necessary todevelop new power voltage supplier for use in the semiconductor memorydevice which is adaptive for stably supplying the power voltage withoutincreasing the cell area.

SUMMARY OF INVENTION

It is, therefore, an object of the present invention to provide a powervoltage supplier for stably supplying a noise-free power voltage withoutincreasing a size of a reservoir capacitor.

It is, therefore, another object of the present invention to provide asemiconductor memory device incorporating therein a power voltagesupplier for stably supplying a noise-free power voltage withoutincreasing a size of a reservoir capacitor.

In accordance with an aspect of the present invention, there is provideda power voltage supplier of a semiconductor memory device, including: afirst power voltage supply line for supplying a first power voltage; asecond power voltage supply line for supplying a second power voltage; afirst reservoir capacitor for supplying the first and the second powervoltages stably; and a reservoir capacitor controller for selectivelyconnecting the first reservoir capacitor to the first power voltagesupply line or the second power voltage supply line.

In accordance with another aspect of the present invention, there isprovided a semiconductor memory device incorporating therein a powervoltage supplier, including: a bit line sense amplifier (BLSA) arrayprovided with a plurality of bit line sense amplifiers for sensing andamplifying data of bit lines; a power voltage supply means including afirst, a second and a third power voltage suppliers for supplying afirst, a second and a third power voltages, respectively; a BLSA drivingcontrol signal generation means for generating a pre-driving controlsignal and a BLSA driving control signal, after receiving an activecommand; a reservoir capacitor control means for selectively connectinga reservoir capacitor to the first power voltage supplier or the secondpower voltage supplier; an overdriving control signal generator forreceiving the BLSA driving control signal to generate an overdrivingcontrol signal; and a BLSA driver for driving the bit line senseamplifier with the third power voltage during a first predetermined timeand for overdriving the bit line sense amplifier with the first powervoltage during a second predetermined time.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and features of the present invention willbecome apparent from the following description of preferred embodimentstaken in conjunction with the accompanying drawings, in which:

FIG. 1 is a block diagram setting forth a prior art semiconductor memorydevice incorporating therein a power voltage supplier;

FIG. 2 is a timing diagram setting forth an operation of the prior artsemiconductor memory device;

FIG. 3 is a circuit diagram setting forth a semiconductor memory devicewith a power voltage supplier in accordance with a preferred embodimentof the present invention;

FIG. 4 is a block diagram setting forth the power supplier of thesemiconductor memory device in accordance with the preferred embodimentof the present invention; and

FIG. 5 is a timing diagram setting forth an operation of thesemiconductor memory device in accordance with the preferred embodimentof the present invention.

DETAILED DESCRIPTION OF INVENTION

Hereinafter, a semiconductor memory device incorporating therein a powervoltage supplier in accordance with the present invention will bedescribed in detail referring to the accompanying drawings.

FIG. 3 is a circuit diagram setting forth a power voltage supplier wherea reservoir capacitor is shared between a VPP voltage supplier and a VDDvoltage supplier in accordance with a preferred embodiment of thepresent invention.

Referring to FIG. 3, the power voltage supplier of the present inventionincludes a VDD voltage supply line 120 for supplying a VDD voltage, afirst reservoir capacitor 130 connected to the VDD voltage line 120 forstabilizing a voltage level, a VPP voltage supply line 220 for supplyinga VPP voltage, a second reservoir capacitor 440 selectively connected tothe VDD voltage supply line 120 and the VPP voltage supply line 220, anda reservoir capacitor controller 320. Herein, the reservoir capacitorcontroller 320 connects the second reservoir capacitor 440 to the VDDvoltage supply line 120 while the VDD voltage is consumed withoutconsumption of the VPP voltage or connects the second reservoircapacitor 440 to the VPP voltage supply line 220 while the VPP voltageis much consumed in such a case that the word line WL is turned on/off.

The reservoir capacitor controller 320 is provided with a first switchSW1 and a second switch SW2, wherein the first switch SW1 connects thesecond reservoir capacitor 440 to the VDD voltage supply line 120 inresponse to a control signal CAPC which is activated when the VDDvoltage is consumed without consumption of the VPP voltage, and thesecond switch SW2 connects the second reservoir capacitor 440 to the VPPvoltage line 220 in response to the control signal CAPC.

In detail, when the control signal CAPC becomes in logic low level, thesecond reservoir capacitor 440 is connected to the VPP voltage supplyline 220. On the contrary, when the control signal CAPC becomes in logichigh level, the second reservoir capacitor 440 is connected to the VDDvoltage supply line 120. Therefore, the first and the second reservoircapacitors 130 and 440 are connected to the VDD voltage line 120 whilethe control signal CAPAC is in logic high level so that it is possibleto supply the VDD voltage stably in comparison with the prior art.

That is, in case that specific operational periods that consume the VDDpower voltage and the VPP power voltage are not overlapped each other,the inventive power voltage supplier employs such a sharing scheme thatthe second reservoir capacitor 440 is selectively connected to the VDDvoltage supply line 120 and the VPP voltage supply line 220 according toan activation state of the control signal CAPC. As a result, it ispossible to supply the VDD power voltage having a stable voltage levelin a virtue of the second reservoir capacitor 440 without furtherincreasing a size of the first reservoir capacitor connected to the VDDvoltage supply line 120.

FIG. 4 is a block diagram setting forth the semiconductor memory devicehaving the power voltage supplier in accordance with the preferredembodiment of the present invention.

Referring to FIG. 4, the inventive semiconductor memory device with thepower voltage supplier includes a memory cell array 100 having aplurality of memory cells, a bit line sense amplifier (BLSA) array 120having a plurality of bit line sense amplifiers, a VPP voltage supplier400 provided with a VPP voltage generator 420 and a reservoir capacitor440 for supplying a VPP voltage, a word line driver 140, a VDD powervoltage supplier 500 for supplying a VDD voltage, a VCORE voltagesupplier 260 for supplying a VCORE voltage, a BLSA driving controlsignal generator 270, a reservoir capacitor controller 300, anoverdriving control signal generator 280 and a BLSA driver 290.

Herein, the BLSA array 120 senses a potential difference of the bit linepair BL and /BL and amplifies a voltage level of a bit line pair BL and/BL of the memory cell array 100. The word line driver 140 drives a wordline WL of the memory cell array 100 arranged in a same row with the VPPvoltage in response to an active command signal ACT, to thereby activatethe memory cells corresponding to the word line WL. The BLSA drivingcontrol signal generator 270 receives the active command signal ACT andgenerates a pre-driving control signal SA_ACT_PRE and a BLSA drivingcontrol signal SA_ACT. The reservoir capacitor controller 300selectively connects the reservoir capacitor 440 to an output node ofthe VPP voltage generator 420 or an output node of the VDD voltagesupplier 500 after receiving the pre-driving control signal SA_ACT_PRE.The overdriving control signal receives the driving control signalSA_ACT and thus, generates an overdriving control signal. The BLSAdriver 290 generates a driving voltage signal RTO for driving the bitline sense amplifier with the VCORE voltage by receiving the BLSAdriving control signal SA_ACT, and particularly overdrives the bit linesense amplifier with the VDD voltage at an initial operation stage, inresponse to the overdriving control signal.

The reservoir capacitor controller 300 is provided with a control signalgenerator 310 and a switching unit 320. The control signal generator 310generates and activates a control signal CAPC in response to thepre-driving control signal SA_ACT_PRE, wherein an activation period B ofthe overdriving control signal exists within an activation period D ofthe control signal CAPC. The switching unit 320 connects the reservoircapacitor 440 selectively to the output node of the VPP voltagegenerator 420 or the output node of the VDD voltage generator 500. Asshown in FIG. 3, the switching unit 320 is provided with the firstswitch and the second switch for selectively connecting the reservoircapacitor to the VDD voltage supplier 500 or the VPP voltage supplier420.

FIG. 5 is a timing diagram setting forth an operation of thesemiconductor memory device in accordance with the preferred embodimentof the present invention.

To begin with, the word line driver 140 applies the VPP voltage to theword line in response to the active command ACT so that the data of thememory cell connected to the word line WL is applied to the bit line.Such an operational period is denoted as A in FIG. 5. In addition, theBLSA driving control signal generator 270 activates the pre-drivingcontrol signal SA_ACT_PRE, and then activates the BLSA driving controlsignal SA_ACT in response to the active command signal ACT after apredetermined time is passed from an activation point of the pre-drivingcontrol signal SA_ACT_PRE.

Afterwards, the BLSA driver 290 drives the bit line sense amplifier withthe VCORE voltage in response to the BLSA driving control signal SA_ACT,and particularly overdrives the bit line sense amplifier with the VDDvoltage at the initial operation stage while the overdriving controlsignal is activated. At this time, since the control signal generator310 activates the control signal CAPC in response to the activatedpre-driving control signal SA_ACT_PRE and then maintains an active statefor the activation period D, the reservoir capacitor 440 is connected tothe output node of the VDD voltage supplier 500 within the activationperiod D of the control signal CAPC.

Thereafter, when a precharge signal PCG is applied to deactivate theword line, the bit line pair BL and /BL is precharged to a prechargevoltage level VBLP, which is denoted as C in FIG. 5.

The inventive semiconductor memory device connects the reservoircapacitor 440 to the output node of the VDD voltage supplier 500 duringthe activation period D of the control signal CAPC so that it ispossible to prevent the voltage level of the VDD voltage from beingdropped due to a lot of current consumption at the initial operationstage of the bit line sense amplifier. In addition, the reservoircapacitor 440 is connected to the output node of the VPP voltagegenerator 420 when the control signal CAPC is deactivated so as toprepare a precharge operation in which the VPP voltage is much consumed.

As described above, in accordance with the power voltage supplier of thepresent invention, the reservoir capacitor of the VPP voltage supplieris shared with the VDD voltage supplier, which is controlled by thecontrol signal CAPC. That is, since the VPP voltage level is unstable incase of consuming the VPP voltage substantially, e.g., in case of theword line being turned on/off, it is difficult to implement the sharingscheme of the reservoir capacitor during these cases. Except thesecases, meanwhile, as the VPP voltage level is not unstable, e.g., in theoperational period of the bit line sense amplifier, it is possible toemploy the sharing scheme of the reservoir capacitor between the VDDvoltage supplier and the VPP voltage supplier.

Accordingly, it is possible to maintain the voltage level of the VDDvoltage without noise while the bit line sense amplifier performs asensing and an amplifying operation and thus, to achieve thesemiconductor memory device operable with high reliability.

Meanwhile, though the reservoir capacitor of the VPP voltage supplier isshared with the VDD voltage supplier in the preferred embodiment becausethe operational periods utilizing the VDD voltage and the VPP voltageare not overlapped each other, the inventive sharing scheme of thereservoir capacitor can be applied to the other power voltage supplierswhere specific operational periods are not overlapped each other.

The present application contains subject matter related to the Koreanpatent application No. KR 2004-70846, filled in the Korean Patent Officeon Sep. 6, 2004, the entire contents of which being incorporated hereinby reference.

While the present invention has been described with respect to theparticular embodiments, it will be apparent to those skilled in the artthat various changes and modifications may be made without departingfrom the spirit and scope of the invention as defined in the followingclaims.

1. A semiconductor memory device, comprising: a first power voltagesupply line for supplying a first power voltage to overdrive at leastone bit line sense amplifier with the first power voltage during apredetermined time at an initial driving stage of the bit line senseamplifier; a second power voltage supply line for supplying a secondpower voltage to drive at least on word line with the second powervoltage; a first reservoir capacitor for supplying the first and thesecond power voltages stably; and a reservoir capacitor controller forselectively connecting the first reservoir capacitor either to the firstpower voltage supply line or the second power voltage supply line,wherein the first power voltage supply line is connected to the firstreservoir capacitor during the predetermined time.
 2. The semiconductormemory device as recited in claim 1, wherein the reservoir capacitorcontroller comprises: a control signal generator for generating acontrol signal; and a switching unit for selectively connecting thefirst reservoir capacitor either to the first power voltage supply lineor the second power voltage supply line in response to the controlsignal.
 3. The semiconductor memory device as recited in claim 2,wherein the switching unit comprises: a first switch for connecting thefirst reservoir capacitor to the first power voltage supply line whenthe control signal is activated; and a second switch for connecting thefirst reservoir capacitor to the second power voltage supply line whenthe control signal is deactivated, wherein the control signal isactivated during the predetermined time.
 4. The semiconductor memorydevice as recited in claim 1, further comprising a second reservoircapacitor for maintaining a voltage level of the first power voltagestably, which is connected to the first power voltage supply line. 5.The semiconductor memory device as recited in claim 1, wherein the firstpower voltage is a VDD voltage corresponding to an external powervoltage and the second power voltage is a VPP voltage having a voltagelevel greater than that of the VDD voltage.